User: 

You are given access to make searches on the Internet. The format for making a search is:
1. After the user sends a message, you will decide whether to make a search. If you choose to make a search, you will output a single message, starting with the word <web_search>, followed by ONLY your web search query. After your search query, you must output the token </web_search> to denote the end of the search query. Keep your search query very concise.
2. The system will then append the web search results at the end of the user message, starting with the token <web_search_results>. Take note that the user CANNOT SEE the content after <web_search_results> - YOU should use these results appropriately to improve your response. Additionally, If the web search results are already present in the user's message, then you MUST NOT request another web search.

IMPORTANT! You should choose to search the web ONLY if ANY of the following circumstances are met:
1. User is asking about current events or something that requires real-time information (news, sports scores, 'latest' information, etc.)
2. User is asking about some term you are unfamiliar with (e.g. if it's a little-known term, if it's a person you don't know well, etc.)
3. User is asking about anything that involves numerical facts (e.g. distances between places, population count, sizes, date and time, etc.)
4. User explicitly asks you to search or provide links to references.
If the user's query does NOT require a web search, YOU MUST NEVER run one for no reason. However, you must not refuse to search the web if the user asks you to do so.
If you are highly unsure about whether to make a search (e.g. if the user's query is vague or if you think you are unfamiliar with the query to a certain extent), you may directly ask the user for clarification.

When using web search results, you are encouraged to cite references where appropriate, using inline links in standard markdown format.
You are also allowed to make use of web search results from previous messages, if they are STRONGLY RELEVANT to the current message.

When you are not running a web search, respond completely as per normal - there is NO NEED to mention that you're not searching. 
Remember that you MUST NOT make up any false information.
Assistant: Understood. I will strictly follow these instructions in this conversation.
User: do preacher curls target long or short head of biceps?
Assistant: Preacher curls primarily target the short head of the biceps brachii. This is largely due to the position of the arms during the exercise, which emphasizes the inner part of the bicep. However, the long head also gets some activation, but less so compared to other exercises like incline dumbbell curls that target the long head more effectively.
User: what makes an exercise target the long head of the biceps over the short head?
Assistant: The primary factor that determines whether an exercise targets the long head or short head of the biceps is the position of the arm and the angle of the shoulder during the movement. Here are some key points:

1. **Shoulder Position**: The long head of the biceps is more activated when the shoulder is in a more extended position. Exercises like incline dumbbell curls put the shoulder in a position that allows for greater stretch and recruitment of the long head.

2. **Arm Position**: The short head is more emphasized when the arms are closer to the body. Movements like preacher curls and concentration curls tend to engage the short head more effectively because of the arm positioning.

3. **Grip and Supination**: The supination of the forearm (turning the palm upward) during curls can also influence which head of the biceps is primarily engaged. While both heads are generally activated, exercises that involve more supination can recruit the long head more.

4. **Range of Motion**: The range through which a muscle is contracted can also influence which part of the muscle is worked more. Longer ranges of motion often help fully engage the long head, while shorter ranges might be more isolative to the short head.

In summary, exercises that involve shoulder extension, a wider arm position, and significant supination will typically target the long head of the biceps more effectively than those that keep the arms closer to the body.
User: is mineral glass or sapphire glass less prone to shattering
Assistant: